Signal loss occurs for signals transmitted across an RG-6 cable connecting an indoor unit with an outdoor unit. During installation, linear VSAT terminal installers may manually calibrate for signal loss between the indoor unit and the outdoor unit using separate handheld devices to measure the signal loss at an output of various components. Manual calibration may be a lengthy process, which may include introduction of human errors. After the manual calibration is completed, the manual calibration is to be repeated when any parameter related to transmit signal power between the indoor unit and the outdoor unit changes. An example of such a parameter includes, but is not limited to, a change in length of a cable connecting the indoor unit with the outdoor unit.
FIG. 1 illustrates use of a previous method for automatic calibration of linear radio transmit signals. FIG. 1 shows an indoor unit 108 connected to an outdoor linear radio 112 of an outdoor unit via a RG-6 cable 124. Indoor unit 108 includes an automatic level control circuit 104 for controlling a power level of transmit signals sent from indoor unit 108 to outdoor linear radio 112. Outdoor linear radio 112 includes a demultiplexer 114, an upconverting mixer 106, a coupler 116, and a power detector 102. In FIG. 1, indoor unit 108 may transmit multiple multiplexed signals to outdoor linear radio 112 via RG-6 cable 124. Demultiplexer 114 receives and demultiplexes the multiple signals to produce a transmit signal 118 of an intermediate frequency, as well as other signals. Upconverting mixer 106 receives transmit signal 118 and a local oscillator signal 120 to produce a transmit signal at a final output frequency 122. Coupler 116 simultaneously provides transmit signal 122 to power detector 102 and a Very Small Aperture Terminal (VSAT) antenna 126, which transmits transmit signal 122 to a destination device via a satellite. Power detector 102 measures a power level of transmit signal 122 and provides power information to automatic level control circuit 104 via a digital communication link 110.
Automatic level control circuit 104, in indoor unit 108, receives the power information as feedback, thereby causing automatic level control circuit 104 to control, based on the power information, a power level of transmit signals transmitted to outdoor linear radio 112 via RG-6 cable 124 connecting indoor unit 106 with outdoor linear radio 112.